The young woman was arrested following her protest on 27 December, according to lawyer Nasrin Sotoudeh. She is said to have been released after the social media campaign '#Where_is_She?' heaped pressure on authorities.

In recent years, Iranian women have started marching against the restrictive Islamic dress code by sharing images of themselves with their hair uncovered on social media, tagged #whitewednesdays.

The woman, named "girl of Enghelab street" after the location of her protest, was filmed without her headscarf, while standing on a pillar box in Tehran last December.

She had tied it to a stick in an apparent reference to the white Wednesday protests against Iran's strict interpretation of Islamic law on female modesty.

The girl of Enghelab street appears to have sparked a protest movement. Since the video of her protest went viral, Iranian women have been sharing pictures of themselves waving their headscarves from sticks in a public act of defiance.

At least six women shared images of their white Wednesday protests on social media on Monday (29 January), copying the symbolic gesture of the girl of Enghelab street with their hijabs tied to a stick.

"My guess is that more of these protests will follow," Sotoudeh told the New York Times. "It's obvious that some women want to decide for themselves what to wear."

Last month, Sotoudeh said the girl of Enghelab's protest clearly showed someone who was "at the end of their tether because of all the controls placed on her body over the 31 years of her life".

"Women feel they have no control over their bodies. It is a prelude to infringing all their rights," she said.